INTRODUCTION

Install git, check (https://git-scm.com/book/en/v2/Getting-Started-Installing-Git) for easy and clear installation.

After installation, ensure you configure your username and email before making any commit. It allows commits to have right author name and email associated to them. However, this has nothing to do with authentication when pushing to a remote repo.

SETTING YOUR USER NAME AND EMAIL

Git config --global user.name "my_username"
Git config --global user.email my_mail@example.com

The above commands declares identity for all repositories, to declare an identity for a single repository, use git config inside a repo

Example:

cd my_repository
git config user.name "my_work_login"
git config user.email my_work_mail@example.com

Remove a global identity

git config --global --remove-section user.name
git config --global --remove-section user.email

However, to force git to look for your identity only within a repository's settings, not in the global config

git config --global user.useConfigOnly true

Tip: Settings stored in a repository's config file will take precedence over the global config when you use that repository

CREATING, ADDING AND COMMITING FILES

git --version - verifies if git is installed

Configuring user information, initializing and cloning repositories (starting a project)

git init – initiates or creates an empty repository. It creates a hidden folder(.git) necessary for git to work

git clone<project_name> - copies an existing Git repository from a server to the local machine. It is followed by a url for the repository that is being cloned.

Example: git clone https://github.com/my_username/my_project.git
NB: You can also use the ssh version of the command:
git clone git@github.com:my_username/my_project.git
However, GitHub recommends using https rather than ssh.

Working with snapshots and the Git staging area

git status - checks what files Git will add to your new repository

git add <file> - tells Git which of the files to place into version control

git add . - tell Git place everything in the directories and the sub-directories into version control.

git reset <file> - unstage a file while retaining the changes in working directory

git diff - difference of what is changed but not staged

git diff --staged - difference of what is staged but not yet committed

NB: create and populate a file named .gitignore before running the add command for files that you want to exclude from being tracked by Git

git commit -m "Initial commit" – commits all the added files
A commit creates a snapshot of your entire project. After a commit, the project is ready to upload to a remote repository

git remote add origin <https://<your-git-service-address>/owner/repository.git>

NB: You have to create a repository in your git service before adding the created remote.

BRANCHING AND MERGING

git branch - list your branches. a * will appear next to the currently active branch

git branch [-a] - List all local branches in repository.With -a: show all branches(with remote).

git branch -d [name] - Remove selected branch, if it is already merged into any other. -D instead of -d forces deletion.

git checkout [-b][branch_name] - Switch working directory to the specified branch. With -b: Git will create the specified branch if it does not exist.

git branch <branch-name> - create a new branch at the current commit

git checkout - switch to another branch and check it out into your working directory

git merge <branch> - merge the specified branch’s history into the current one

git log branchB..branchA - show the commits on branchA that are not on branchB

SETTING UP THE UPSTREAM REMOTE

if you clone a fork, most probably you will not be able to push access to the upstream repo, so you need both your fork but be able to fetch the upstream repository.

git remote -v - check the remote names

example:

git remote -v 
origin https://github.com/myusername/repo.git (fetch)
origin https://github.com/myusername/repo.git (push)
upstream # this line may or may not be here

If upstream is there already, set the URL

git remote set-url upstream https://github.com/projectusername/repo.git

if it is not there, or you want to add a friend’s fork

git remote add upstream https://github.com/projectusername/repo.git
git remote add emma_donery https://github.com/emma_donery/repo.git

FINDING INFORMATION ABOUT A COMMAND

The help command gives details about what the command does, available options and
other documentation.
Syntax:
git command_name --help
example
git push --help

GETTING UPDATES FROM OTHER REPOS AND UPDATING THE LOCAL REPOSITORY

git remote add [alias] [url] - add a git URL as an alias

git fetch [alias] - Fetch down all the branches from that Git remote

git merge [alias]/[branch] - merge a remote branch into your current branch to bring it up to date

git push [alias] [branch] - Transmit local branch commits to the remote repository branch

git pull - fetch and merge any commits from the tracking remote branch